The present invention relates to a satellite repeater for satellite communications, and more particularly to a satellite repeater which is suitable for use in a digital satellite communication system utilizing time division multiple access (TDMA) or frequency division multiple access (FDMA) techniques.
The most common traditional system for satellite communications is an FDM-FM-FDMA system. In order to answer the increasing number of earth stations in the system and of traffic, however, the introduction of digital satellite communication systems has been studied which are of higher efficiency and larger capacity and capable of flexibly following up traffic variations. As a result, there has already been put to practical use a system, called Satellite Switched TDMA (SS/TDMA), in which a multi-spot beam satellite and the TDMA techniques are combined, a dynamic switch is provided on the satellite and the beams are switched at a high speed in synchronism with TDMA frames. In the conventional system, it is necessary for each earth station to control the transmit timing of its signal to synchronize it with the switching timing of the dynamic switch matrix on board the satellite; to perform this, the earth station calls for an initial synchronizer and equipment for maintaining the synchronization of the timings.